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Core recurrence

T²MLR

T^2MLR: Transformer with Temporal Middle-Layer Recurrence

Ziyang Cai, Xingyu Zhu, Yihe Dong, Yinghui He, Sanjeev Arora

Temporal Middle-Layer Recurrence fuses a cached middle-layer representation from the previous token into an earlier layer at the current position, letting intermediate computation persist across decoding steps with little overhead and without looping all layers.

Inside the method

token t−1: middle layer → fused into early layer of token t

Simplified conceptual schematic. Consult the paper for the complete architecture.

Recurrence family
Core recurrence
Depth control
One forward per token; recurrence across time
KV / state strategy
Cached middle-layer state from the previous token

Reading note

Beats data- and parameter-matched Transformers in pretraining and multi-hop reasoning; recurrence over as little as 20% of the network often beats full-layer recurrence. Can be retrofitted into a pretrained 1.7B model with brief fine-tuning.

Sources checked 2026-10-28. This catalog does not imply independent reproduction.

Related works

Cite this work

@misc{t2mlr2026,
  title = {T^2MLR: Transformer with Temporal Middle-Layer Recurrence},
  author = {Ziyang Cai and Xingyu Zhu and Yihe Dong and Yinghui He and Sanjeev Arora},
  year = {2026},
  eprint = {2607.15178},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2607.15178}
}

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